The aim of the present study was to evaluate the antioxidant activity of marine red algae Chondrococcus hornemannii and Spyridia fusiformis. The methanolic extract of the algae C. hornemannii and S. fusiformis screened for antioxidant activities against superoxide and ABTS free radicals and were compared to that of standard BHT and α-tocopherol. The phenolic related compounds are mainly responsible for the higher rate of antioxidant activity. These results indicated that both seaweeds could be potential sources of development novel antioxidant compounds.